Quaternary Science Reviews 30 (2011) 2309e2328 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Last straw versus Blitzkrieg overkill: Climate-driven changes in the Arctic Siberian mammoth population and the Late Pleistocene extinction problem P.A. Nikolskiy a,*, L.D. Sulerzhitsky a, V.V. Pitulko b a Geological Institute of the Russian Academy of Sciences, Pyzhevsky per. 7, 119017 Moscow, Russia b Institute for the Material Culture History, Russian Academy of Sciences, Dvortsovaya nab. 18, 191186 Saint Petersburg, Russia article info abstract Article history: A set of radiocarbon dates on woolly mammoth were obtained from several regions of Arctic Siberia: the Received 8 December 2009 New Siberian Islands (n ¼ 68), north of the Yana-Indigirka Lowland (n ¼ 43), and the Taimyr Peninsula Received in revised form (n ¼ 18). Based on these and earlier published dates (n ¼ 201) from the East Arctic, a comparative analysis 22 October 2010 of the time-related density distribution of 14C dates was conducted. It was shown that the frequencies of Accepted 26 October 2010 14C dates under certain conditions reflect temporal fluctuations in mammoth numbers. At the end of the Available online 27 November 2010 Pleistocene the number of mammoths in the East Arctic changed in a cyclic manner in keeping with a general “Milankovitch-like” trend. The fluctuations in numbers at the end of the Pleistocene occurred synchronously with paleoenvironmental changes controlled by global climatic change. There were three minima of relative mammoth numbers during the last 50 000 years: 22 000, 14 500e19 000, and 9500 radiocarbon years ago, or around 26 000, 16e20 000, and 10 500 calendar years respectively. The last mammoths lived on the New Siberian Islands, which were connected to the continent at that time, 9470 Æ 40 radiocarbon years ago (10 700 Æ 70 calendar years BP). This new youngest date approximates the extinction time of mammoths in the last continental refugium of the Holarctic. The adverse combination of environmental parameters was apparently a major factor in the critical reduction in mammoth numbers. The dispersal of humans into the Arctic areas of Siberia no later than 28 000 radiocarbon years ago did not overtly influence animal numbers. Humans were not responsible for the destruction of a sustainable mammoth population. The expanding human population could have become fatal to mammoths during strong the minima of their numbers, one of which occurred at the very beginning of the Holocene. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction interspecies and intraspecies competition, disease, and other natural factors. We attribute the astronomical impact hypothesis for The last non-compensated extinctions among large terrestrial Pleistocene extinction to this group of factors, as the impact event mammals started roughly 40 000 years ago, becoming more (if it ever took place) would have operated indirectly, triggering the pronounced towards the end of the Pleistocene. Possible causes of mentioned environmental factors. the extinction have been a topic of discussion for more than 150 2. Extermination by humans. There are many extinction models years. Nearly all of the known hypotheses concerning the disap- in which some of the named factors operate jointly. Different pearance of certain taxa or entire faunas were put forward in the authors have varying ideas regarding the principal model (see for 19th century (Pavlova, 1924; Grayson, 1984). At present, there are example: Martin and Steadman, 1999; Barnosky et al., 2004; two frequently mentioned causes of this extinction (see Barnosky Whitney-Smith, 2004; Wroe et al., 2004; Guthrie, 2006; Wroe et al., 2004; Koch and Barnosky, 2006 for a review): et al., 2006). 1. Transformation of the environment caused by global climatic For a long time, testing these hypotheses has been severely changes, appearing as fluctuations of temperature, humidity, depth hampered by a lack of direct evidence for dependence of animal of snow cover, wind, change of composition and decrease in population sizes upon any particular factor (natural or anthropo- productivity of vegetation, changes in landscapes, soil geochemistry, genic). The recent widespread use of different dating techniques, especially radiocarbon age measurement, has begun to supply the necessary data. * Corresponding author. Tel.: þ7 916 9354872. E-mail addresses: [email protected] (P.A. Nikolskiy), [email protected] Each direct radiocarbon date on a bone, even if not found in situ, (V.V. Pitulko). uniquely corresponds to three parameters: 0277-3791/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2010.10.017 2310 P.A. Nikolskiy et al. / Quaternary Science Reviews 30 (2011) 2309e2328 1. The animal species (if known). colder climatic conditions would have led to expansion of steppe- 2. The bone location (if known). like landscapes, favorable for abundant and diverse Pleistocene 3. The radiocarbon date of the animal’s death. fauna (Guthrie, 1990; Sher, 1997; Yurtsev, 2001). During interglacial periods, this region served as a refugium for the Pleistocene fauna If the taphonomic biases are low, a sufficient number of dates (Boeskorov, 2006; Lister and Stuart, 2008) because it preserved the allows for reconstruction of the spatio-temporal dynamics of animal conditions of the colder periods of the Pleistocene. Therefore, this ranges and abundance. Furthermore, the radiocarbon method region is one of the world’s largest sources of Late Pleistocene allows for precise dating of some natural and anthropogenic mammal remains. processes. A joint comparative analysis of densely-dated sequences We selected mammoths, Mammuthus primigenius (Blu- is one of the most promising methods to search for cause-effect menbach), as the subject of study because their remains are well relationships of the Late Pleistocene extinction (Martin, 1984; represented in the material collected by the “Zhokhov-Yana” project Guthrie, 1990, 2006; Sulerzhitsky, 1995; Graham et al., 1996; and are the most suitable for conventional radiocarbon dating, Sulerzhitsky and Romanenko 1997; Vasil’chuk et al., 1997; Sher, which requires large samples. In addition, the dates on mammoth 1997; Bocquet-Appel et al., 2005; Orlova et al., 2001; available from the literature, which we included in the analysis, are MacPhee et al., 2002; Stuart et al., 2002; Kuzmin et al., 2003; most abundant. Finally, the mammoth was one of the dominant Barnosky et al., 2004; Gamble et al., 2004; Kuzmin and Orlova, members of the Late Pleistocene (“ Mammoth”) Fauna of the 2004; Orlova et al., 2004; Stuart et al., 2004; Sher et al., 2005; Holarctic and it definitely played a role in the human economy, as Stuart, 2005; Ugan and Bayers, 2007; and many other authors). mammoth remains occur in many Paleolithic sites. The significant By the late 1980s, numerous fossil localities of northeastern Asia number of new reliable dates with accurate sampling, and careful had yielded a large series of 14C dates on mammoth bone collagen analysis of the dating results, enable a study of short-period fluc- (Orlova, 1979; Lavrov and Sulerzhitsky, 1992; Sulerzhitsky, 1995; tuations in frequencies of radiocarbon dates. This makes possible Sulerzhitsky, 1997; Sulerzhitsky and Romanenko, 1997). The anal- a detailed comparison between the dynamics of mammoth ysis of these data revealed a distribution of dates over time resem- numbers, environmental fluctuations and human impact. bling in shape the well-known climatic trend of the terminal Contrary to other regions of Eurasia where the “Mammoth Pleistocene. Most dates are concentrated within the 45e24 ka Fauna” coexisted with people for a longer time, the northern region interval (all dates quoted uncalibrated), which preceded the of the Eastern Arctic was not populated by humans until a relatively beginning of the last glacial maximum (LGM). Within the LGM late period. This provides an important opportunity to evaluate the (23e15 ka), the number of dates strongly decreases, followed by “Blitzkrieg overkill” hypothesis for northernmost Asia. The Blitz- a short-term increase. In the interval corresponding to the early krieg overkill hypothesis assumes that people destroyed a sustain- Holocene, the number of dates sharply decreases to zero, indicating able megamammal population shortly after first contact. The the time of mammoth extinction (in Wrangel [Vartanyan et al.,1993, alternative “Last straw” hypothesis assumes a low influence of 1995, 2008; Vartanyan, 2007] and Pribilof Islands (Guthrie, 2004; humans on the sustainable mammal population, but a human- Veltre et al., 2008) woolly mammoths survived somewhat longer). induced extinction of megamammal populations stressed by The subsequent considerable increase in the number of radio- adverse environmental conditions. carbon dates suggests that the general trend remains unchanged (compare Sulerzhitsky, 1997; Sher et al., 2005); and general trends 2. Methods and material (but not details) of date distribution from different areas of Arctic Siberia and northern North America are much alike (compare There are two hypotheses requiring evaluation prior to the Matheus et al. (2003), Guthrie (2004), and Sher et al. (2005)). It was analysis of human vs. naturally-induced causation of mammoth suggested that this stability in the temporal distribution of dates extinction in Arctic Siberia: and its spatial consistency is not coincidental and is indicative